1. Field of Invention
The present invention relates generally to the field of communications systems, and more particularly in one exemplary aspect, to wireless systems that allow user devices to authenticate to wireless networks (e.g., cellular networks, WLANs, WMANs, etc.) using access control clients.
2. Description of Related Technology
Access control is required for secure communication in most prior art wireless radio communication systems. As an example, one simple access control scheme might comprise: (i) verifying the identity of a communicating party, and (ii) granting a level of access commensurate with the verified identity. Within the context of an exemplary cellular system (e.g., Universal Mobile Telecommunications System (UMTS)), access control is governed by an access control client, referred to as a Universal Subscriber Identity Module (USIM) executing on a physical Universal Integrated Circuit Card (UICC). The USIM authenticates the subscriber to the UMTS cellular network. After successful authentication, the subscriber is allowed access to the cellular network.
Typical implementations of SIM cards contain EEPROM (Electrically Erasable Programmable Read-Only Memory) or flash memory media for storing data (e.g., user data, etc.) Unfortunately, EEPROMs can only be erased a limited number of times before becoming unreliable. For this reason, internal memory controllers also track wear and movement of data. The memory controller uses so-called “wear-leveling” techniques to manage data accesses so that erasures and re-writes are evenly distributed. Wear-leveling ensures that no single area of the EEPROM media fails due to excessive write/erase cycling.
Existing USIM solutions are hard-coded to the physical UICC card media; the subscriber needs a new UICC to change USIM operation. This can be detrimental to both MNOs and subscribers; for example, if the authentication procedures are “broken” (e.g., via malicious “hacking” or other such activities), the subscriber must be issued a new UICC, and this process is both time consuming and expensive. Moreover, for reasons described in greater detail subsequently herein, the physical UICC only contains a single USIM entity; existing solutions are not suitable for handling multiple USIM profiles within the same UICC.
However, there are several benefits stemming from the physicality of the UICC card itself. Specifically, unlike software which can be replicated easily, the card is a physical element which is more difficult to reproduce. The physical barrier to reproduction provides tangible benefits for distribution, sale, piracy, etc. For example, a would-be software pirate cannot sell multiple copies of the same SIM card. Moreover, since “cloning” or copying a SIM card is generally illegal, the one valid physical card can be distinguished from illicit clones. Similarly, vendors can use typical inventory management procedures for SIM cards e.g., purchase, store, liquidate, etc. Moreover, some users perceive (whether correctly or not) the physical SIM card as somehow being more secure and less likely to be the subject of surreptitious copying or distribution since, inter alia, the card is ostensibly always in their possession.
Wear leveling is a technique for prolonging the longevity or service life of certain types of erasable computer storage media, such as flash memory used in USB flash drives or solid-state drives. EEPROM and flash memory media have individually erasable segments, each of which can only tolerate a limited number of use cycles before becoming unreliable. Some flash devices include one or more blocks with extended life that can be used by the memory controller to track the movement of data across various memory segments in order to facilitate tracking “wear”.
Wear leveling is a mechanism which arranges data so that erasures and re-writes are distributed more evenly across the entire medium. In this way, no single memory block prematurely fails due to an inordinately high number of write cycles. Conventional file systems such as FAT, UFS, etc. were originally designed for use on magnetic media such as disk drives, and as such rewrite many data structures such as directories repeatedly to the same medium area.
However, wear leveling has heretofore been limited to certain types of devices and operating system constraints, and there has historically only been one USIM profile per card. Prior art wear leveling techniques are not suitable or optimizable for use with “virtual” access clients such as the inventive eSIMs developed by the Assignee hereof and described in greater detail subsequently herein for a variety of reasons discussed in greater detail below.